Nervous and Sensory Systems


Diagram by Jeff Dawson.

The parts of the nervous system (brain, spinal cord, and nerves) are made up of cells called neurons. Neurons are long, specialized cells that can transmit signals to each other. Nerves carry impulses from the sensory organs to the brain where they are processed. The brain is the center of the nervous system. The turtle's brain is much more advanced than that of amphibians, however, it is very primitive when compared to that of mammals or birds. From the brain extends the spinal cord. The spinal cord, protected by the spine and carapace, travels down the back of the turtle. The spinal cord carries information to and from the brain and forms reflexes. Reptiles have twelve crainal nerves. All turtles respond to vibrations, but they can not hear well. Turtles have good eyesight. A transparent scale covers each eye, protecting the eye from dirt, sand, and other objects. The sense of smell in turtles is very advanced. Turtles are able to smell sources of food from long distances. Aquatic turtles are able to smell underwater. The turtle's sense of taste is linked to the sense of smell. The turtle's shell and skin are sensitive to touch.

Parts of the Turtle's Brain
Ofactory NerveNerves that connect the nose to the ofactory lobe.
Ofactory LobePart of the brain that processes smells. Located in the front of the brain.
Cerebral HemisphereLarge area that controls movements, senses, and behavior.
Optic LobesImportant centers in the processing of information from the eyes.
CerebellumFunctions to coordinate movements.
MedullaPart of the brainstem. The medulla controls autonomic functions, such as breathing, heart activity, swallowing, and digestion.
Pituitary Body(also called the Pituitary gland) A gland located at the base of the brain. It produces and stores hormones that regulate the activities of the turtle's body.


2001 by Jeff Dawson. All rights reserved.
Used by Permission